The present invention relates to a non-adhesive strain relief connector for a fiber optic cable. More particularly, the present invention relates to an optical fiber and cover that are disposed with in a metal sleeve, the cover having a tapered portion that positions the cover within the sleeve. The cover and sleeve are simultaneously compressed such that the cover substantially fills the inner volume of the compressed portion of the sleeve. The combination of the lengths and the widths of the cover and sleeve results in a large frictional surface between the sleeve and the cover providing a strong, reliable connection.
Strain relief connectors for fiber optic cables are common in the connector industry. Conventional strain relief connectors have a sleeve surrounding a light transmitting optical fiber or a plurality of light transmitting optical fibers. The optical fibers are generally surrounded or covered and protected by a jacket or buffer material formed from a plastic. The sleeve and the fiber optic cable are then crimped using a crimping tool into a hexagonal or round shape.
Conventional crimping methods do not allow adequate lateral flow of the jacket material, in other words, the jacket material does not substantially flow in a direction perpendicular to the longitudinal axis of the crimp sleeve. A lack of lateral flow forces the buffer material to flow along the longitudinal axis of the crimp sleeve, producing longitudinal flow. Longitudinal flow places tension on the optical fiber, possibly causing damage to or failure of the optical fiber, or changing its optical characteristics.
In addition, conventional crimping methods have a crimp length that is short relative to the diameter of the jacket material. Generally, the length of the crimp is less than four times the buffer material diameter. This short length results in a small area of frictional contact between the inner surface of the crimp sleeve and the outer surface of the buffer material and may make failure of the connector more likely under tensile or thermal stress.
Furthermore, when assembling and crimping conventional connectors, it can be difficult to properly position the polymer cover within the metal tube or sleeve. Many conventional connectors allow the polymer cover to move longitudinally relative to the sleeve. Also, since the polymer cover is generally disposed within the sleeve, it can be difficult to ascertain the exact location of the polymer cover relative to the sleeve.
Examples of prior art fiber optic cable crimp connectors are disclosed in the following U.S. Pat. Nos. 3,655,275 to Seagraves; 4,738,504 to Jones; 5,140,662 to Kumar; 5,317,664 to Grabiec et al.; 5,418,874 to Carlisle et al.; 5,455,880 to Reid et al.
Thus, a continuing need exists for strain relief fiber optic connectors.
Accordingly an object of the present invention is to provide a strain relief connector for a fiber optic cable that has a relatively large frictional area between the inner surface of the crimp sleeve and the cover layer of the fiber optic cable for a strong reliable crimp connector.
Another object of the present invention is to provide a strain relief connector for a fiber optic cable that has a crimped configuration that allows for substantial lateral flow of the cover layer, putting substantially no longitudinal pressure or strain on the optical fiber.
Still another object of the present invention is to provide a strain relief connector for a fiber optic cable that has a crimp sleeve with a length that is long relative to the diameter of the cover layer, providing a large area of frictional engagement between the cover layer and crimp sleeve and the cover layer and optical fiber.
Yet another object of the present invention is to form a strain relief connector that has a cover, which can be optimally positioned within a sleeve.
Still yet another object of the present invention is to provide a crimping tool and strain relief connector that provide optimal crimping of the sleeve and cover in the connector.
The foregoing objects are basically attained by providing a strain relief connector, comprising an optical fiber and a cover enclosing the optical fiber. The cover has an inner surface, an outer surface, a first end and a second end. The first end has a tapered portion extending radially outwardly. A sleeve surrounds the cover, and has a first inner volume and a first interior shoulder. A portion of the outer surface of the tapered portion abuts the first interior shoulder. The sleeve and the cover are simultaneously compressed, forming a compressed portion, the cover and the sleeve deforming such that the cover substantially fills the first inner volume of the sleeve.
The objects are further attained by a crimp tool for a strain relief connector, the strain relief connector being generally cylindrical and having first and second external shoulders. The crimp tool comprises a first crimp portion and a second crimp portion. The first crimp portion has a first generally planar surface with first and second ends. The second crimp portion has a second generally planar surface with third and fourth ends. The first and second surfaces are generally aligned when crimping. The first and second shoulders of the strain relief connector abut the first and third ends and the second and fourth ends, respectively.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.